Electronic control devices and control systems, including haptic devices—are currently used for a multitude of purposes. These devices range from relatively simple devices, such as a force feedback joystick used for playing computer games, to very sophisticated and expensive robotic surgical systems. A basic high-level prior art electronic control system is now described with reference to FIG. 1.
A prior art control system includes master control system 102. The master control system includes a manipulator 103. The manipulator 103 has an effector 104 that is moved by a user (not shown) in three dimensional space. Enabling such movement of the effector 104 are links 108 and joints 106. Each joint 106 rotates in one or more degrees of freedom, allowing movement of the effector 104.
The manipulator 103 sends data about the movement of the effector 104 to the master control device 102. The master control device 102 uses this data to control a slave device 112. The slave device 112 may be a physical slave device—such as a tool on the Mars rover being controlled from Earth or a surgical tool controlled remotely by a surgeon—or the slave device 112 could be a virtual slave device—such as an avatar or vehicle being controlled in a video game.
The master control device 102 uses the manipulator data to generate a control signal to control the slave device 112, and sends the control signal to the slave device 112 via bus 110. Bus 110 may be any communication medium, including a direct fiber optic link, wireless link, USB cable, communication over a public network such as the Internet, or some combination of communication techniques.
The slave device 112 may send back information about what is happening on the slave side, whether physical or virtual. For example, the slave device 112 may be wielding a surgical tool, and send back a signal indicating the position of the surgical tool and various other forces acting on the surgical tool. In a virtual slave device 112, a video game may send back data indicating the position of an avatar in a virtual environment, such as when an avatar has walked into a virtual wall for example.
From the signal received from the slave device 112, the master control system 102 can determine a force feedback to be provided to the manipulator 103. For example, by comparing the control signal sent by the master controller 102 and the data regarding what is happening at the slave device 112, the master controller 102 can determine an appropriate force feedback signal.
The force feedback signal is provided to the manipulator 103. The joints 106 of the manipulator can house or be connected to motors—such as electric or hydraulic motors for example—that can provide force feedback to the user holding the effector 104. Since such haptic devices are well known in the art, they are not described in great detail herein. One example of control system using such haptic devices is the robotic surgical system described in some detail in U.S. Pat. No. 6,493,608 “Aspects of a Control System of a Minimally Invasive Surgical Apparatus,” assigned to Intuitive Surgical, Inc. Some examples of haptic devices that could be used for master control device 102 include, but are not limited to, the PHANTOM line of haptic devices from SenseAble Technologies, Inc. (http://www.sensable.com), and the omega.x line of haptic devices from Force Dimension (http://www.forcedimension.com).
Vehicle control system designers have long been aware of biodynamic feedthrough, defined generally as the effects of vehicle motion feeding through the operator's body to produce unintended forces on the vehicle control interface. In the automotive field, biodynamic feedthrough has been ignored as insignificant, but some effort has been made to mitigate biodynamic feedthrough on a fighter jet control stick, as described in U.S. Pat. No. 4,477,043 “Biodynamic Resistant Control Stick,” assigned to the U.S. Air Force.
The manufacturers of haptic devices and, such as those mentioned above, and other non-haptic control systems, have not contemplated the used of their control devices in dynamic environments, such as moving vehicles, airplanes, space vehicles, and so on. For example, the robotic surgical system described in U.S. Pat. No. 6,493,608 assumes that both master and slave devices are located in a stable environment, such as a hospital.
Furthermore, the manufacturers of haptic devices have also not contemplated that their products will be used in gravitational environments different from Earth's, or in variable gravitational environments, such as in planes, space vehicles, space stations, or extra-terrestrial surface bases.